Impaired small bowel gas propulsion in patients with bloating during intestinal lipid infusion

OBJECTIVE: In healthy individuals, intraluminal lipids delay intestinal gas clearance, and this reflex is exaggerated in patients with irritable bowel syndrome (IBS). Our aim was to determine the site of action of abnormal lipid-induced reflexes in IBS. METHODS: In six patients with (IBS) predominantly complaining of bloating and in six healthy subjects, a mixture of gas (N2, O2, and CO2 in venous proportions to minimize diffusion) was infused (12 mL/min) either into the jejunum or into the ileum for 2 h, with simultaneous perfusion of lipids (0.5 kcal/min) into the proximal duodenum. Rectal gas evacuation was measured by a barostat. Abdominal perception (by a 0-6 scale) and girth changes were measured at 15-min intervals. The effects of jejunal versus ileal gas infusion were compared by paired tests in random order on separate days. RESULTS: IBS patients exhibited significant gas retention during infusion of gas into the jejunum (398 +/- 90 mL vs-210 +/- 105 mL in health, p < 0.05) but not during ileal infusion (-79 +/- 87 mL vs-79 +/- 78 mL in health, NS; p < 0.05 vs jejunal infusion). Gas retention during jejunal gas infusion in IBS patients was associated with significant abdominal distension (11 +/- 3 mm girth increment vs 0 +/- 1 mm during ileal gas infusion and 1 +/- 1 mm in health, p < 0.05 for both) and abdominal symptoms (3.6 +/- 0.6 score vs 2.6 +/- 0.7 score during ileal gas infusion and 1.6 +/- 0.5 score in health, p < 0.05 for both). CONCLUSIONS: In IBS patients intraluminal lipids impair intestinal gas clearance because of upregulated reflex inhibition of small bowel transit, without appreciable colonic effects.     

Colonic gas transit in patients with bloating: the effect of an electromechanical stimulator of the abdominal wall

Background

The aim of our study was to evaluate gas retention, abdominal symptoms and changes in girth circumference in females with bloating using an active or sham abdominal wall mechanical stimulation.

Methods

In 14 female patients, complaining of bloating (11 with irritable bowel syndrome and 3 with functional bloating according to the Rome III criteria) a gas mixture was continuously infused into the colon for 1 h (accommodation period). Abdominal perception and girth were measured. At the beginning of the 30-min period of free rectal gas evacuation (clearance period), an electromechanical device was positioned on the abdominal wall of all patients. The patients were randomly assigned to an active or a sham stimulation protocol group. Gas retention, perception and abdominal distension were measured at the end of the clearance period.

Results

All patients tolerated the volume (1,440 ml) of gas infused into the colon. Abdominal perception and girth measurements was similar in both groups during the accommodation period. At the end of the clearance, the perception score and the girth changes in the active and sham stimulation groups were similar (2.8 ± 2.0 vs. 1.4 ± 1.2, p = 0.2 and 4.9 ± 4.5 vs. 2.8 ± 2.3 mm, p = 0.3 active vs. sham, respectively). Furthermore, the mechanical stimulation of the abdominal wall did not significantly reduce gas retention (495 ± 101 ml vs. 566 ± 55, active vs. sham, p = 0.1).

Conclusions

An external mechanical massage of the abdominal wall did not improve intestinal gas transit, abdominal perception and abdominal distension in our female patients complaining of functional bloating.     

Physical activity and intestinal gas clearance in patients with bloating

BACKGROUND: Patients complaining of abdominal bloating have impaired tolerance and clearance of intestinal gas loads. Mild exercise enhances intestinal clearance and prevents retention of intestinal gas loads in healthy subjects. Our aim was to evaluate the putative beneficial effects of physical activity in patients with abdominal bloating. METHODS: In eight patients complaining of bloating, seven with irritable bowel syndrome, and one with functional bloating, according to Rome II criteria, a gas mixture was continuously infused (12 mL/min) into the jejunum for 120 min with simultaneous duodenal lipid perfusion (1 kcal/min). Gas evacuation, perception (0-6 scale), and abdominal girth were measured at 15-min intervals. Paired studies were randomly performed in the supine position during intermittent pedaling (5 min with 3-min rest intervals at 40 rpm and 0.15 kp load) versus rest (as control). RESULTS: During rest, a significant proportion of the gas infused was retained in the gut (45 +/- 9%, P < 0.01 vs basal), but retention was significantly lower during exercise (24 +/- 7%, P < 0.05 vs rest). Gas retention during rest was associated with significant abdominal symptoms (3.6 score; P < 0.01 vs basal), and symptoms also improved during exercise (2.8 score, P < 0.05 vs rest). During the test, patients developed abdominal distension, which was related to the volume of gas retained (r = 0.68, P < 0.05). CONCLUSION: Mild physical activity enhances intestinal gas clearance and reduces symptoms in patients complaining of abdominal bloating.     

Impaired transit and tolerance of intestinal gas in the irritable bowel syndrome

BACKGROUND: Patients with irritable bowel syndrome (IBS) frequently complain of excessive gas but their fasting volume of intestinal gas is apparently normal. We hypothesised that the pathophysiological mechanism involved may be impairment of intestinal gas transit. AIM: To investigate intestinal gas transit and tolerance in IBS patients compared with healthy subjects. METHODS: A gas mixture (N(2), O(2), and CO(2) in venous proportions) was infused into the jejunum of 20 patients with IBS and 20 healthy controls at 12 ml/min for four hours. Gas evacuation, initially flatus from the anus (two hours) and then intrarectally (two hours), was continuously recorded. Symptom perception (0-6 scale) and abdominal distension were measured at 10 minute intervals. RESULTS: After two hours of external gas (flatus) collection, 18 of 20 IBS patients had developed gas retention (>400 ml), increased gastrointestinal symptoms (score >3), or abdominal distension (>3 mm girth increment) compared with only four of 20 control subjects. During intrarectal gas collection, 13 of 17 patients still exhibited abnormal responses. CONCLUSION: A large proportion of patients with IBS can be shown to have impaired transit and tolerance of intestinal gas loads. This anomaly may represent a possible mechanism of IBS symptoms, specifically pain and bloating.     

Alteration of intestinal microflora is associated with reduction in abdominal bloating and pain in patients with irritable bowel syndrome

OBJECTIVE: The influence of the gastrointestinal (GI) microflora in patients with irritable bowel syndrome (IBS) has not been clearly elucidated. This study was undertaken to see if patients with IBS have an imbalance in their normal colonic flora, as some bacterial taxa are more prone to gas production than others. We also wanted to study whether the flora could be altered by exogenous supplementation. In a previous study we have characterized the mucosa-associated lactobacilli in healthy individuals and found some strains with good colonizing ability. Upon colonization, they seemed to reduce gas formation. METHODS: The study comprised 60 patients with IBS and a normal colonoscopy or barium enema. Patients fulfilling the Rome criteria, without a history of malabsorption, and with normal blood tests underwent a sigmoidoscopy with biopsy. They were randomized into two groups, one receiving 400 ml per day of a rose-hip drink containing 5 x 10(7) cfu/ml of Lactobacillus plantarum (DSM 9843) and 0.009 g/ml oat flour, and the other group receiving a plain rose-hip drink, comparable in color, texture, and taste. The administration lasted for 4 wk. The patients recorded their own GI function, starting 2 wk before the study and continuing throughout the study period. Twelve months after the end of the study all patients were asked to complete the same questionnaire regarding their symptomatology as at the start of the study. RESULTS: All patients tolerated the products well. The patients receiving Lb. plantarum had these bacteria on rectal biopsies. There were no major changes of Enterobacteriaceae in either group, before or after the study, but the Enterococci increased in the placebo group and remained unchanged in the test group. Flatulence was rapidly and significantly reduced in the test group compared with the placebo group (number of days with abundant gas production, test group 6.5 before, 3.1 after vs 7.4 before and 5.6 after for the placebo group). Abdominal pain was reduced in both groups. At the 12-month follow-up, patients in the test group maintained a better overall GI function than control patients. There was no difference between the groups regarding bloating. Fifty-nine percent of the test group patients had a continuous intake of fermented products, whereas the corresponding figure for the control patients was 73%. CONCLUSIONS: The results of the study indicate that the administration of Lb. plantarum with known probiotic properties decreased pain and flatulence in patients with IBS. The fiber content of the test solution was minimal and it is unlikely that the fiber content could have had any effect. This type of probiotic therapy warrants further studies in IBS patients.     

Origin of gas retention and symptoms in patients with bloating

BACKGROUND & AIMS: Patients reporting abdominal bloating exhibit impaired tolerance to intestinal gas loads. The aim of this study was to identify the gut compartment responsible for gas retention. METHODS: In 30 patients predominantly reporting abdominal bloating (24 with irritable bowel syndrome and 6 with functional bloating) and 22 healthy subjects, gas (nitrogen, carbon dioxide, and oxygen) was infused into the intestine for 2 hours while measuring rectal gas outflow. First, in 12 patients and 10 healthy subjects, gas transit (24 mL/min jejunal infusion labeled with 74 MBq bolus of 133 Xe) was measured by scintigraphy. Second, in groups of patients and healthy subjects, the effects of gas infusion (12 mL/min) in the jejunum versus ileum, jejunum versus cecum, and jejunum versus sham infusion (n=6 each) were compared by paired tests. RESULTS: In patients, total gut transit of gas was delayed (50% clearance time, 33 +/- 4 min vs 23 +/- 4 min in healthy subjects; P <.05) owing to impaired small bowel transit (50% clearance time, 20 +/- 2 min vs 12 +/- 3 min in healthy subjects; P <.05), whereas colonic transit was normal (50% clearance time, 13 +/- 2 min vs 11 +/- 2 min in healthy subjects; not significant). Furthermore, jejunal gas infusion in patients was associated with gas retention (329 +/- 81 mL vs 88 +/- 79 mL in healthy subjects; P <.05), whereas direct ileal or colonic infusion was not (61 +/- 103 mL and -143 +/- 87 mL retention, respectively). CONCLUSIONS: In patients reporting bloating, the small bowel is the gut region responsible for ineffective gas propulsion.     

Sensation of bloating and visible abdominal distension in patients with irritable bowel syndrome

OBJECTIVES: Abdominal bloating and distension are common symptoms of irritable bowel syndrome (IBS). The postulated pathophysiological mechanisms underlying these symptoms include increased production, retention, or perception of gas or luminal contents. The aims of this study were to prospectively compare the prevalence of, and clinical factors related to, bloating and distension in an IBS patient population. METHODS: A total of 714 consecutive patients who met Rome I criteria for IBS were prospectively surveyed, and were classified as having bloating alone (B) or bloating and distension (B+D) based on a comprehensive bowel symptom questionnaire. GI, extraintestinal, and psychological symptoms, as well as health-related quality of life measures were also assessed using validated survey instruments. RESULTS: A total of 542 IBS patients (76%) who reported abdominal bloating were studied. Of these, 132 patients fulfilled criteria for the B group, whereas 410 patients fulfilled criteria for the B+D group. There was a significantly different gender distribution in the B and B+D groups (female:male ratios, 1.4:1 and 2.8:1, respectively p < 0.02). There was also a significantly different bowel habit subgroup distribution, with a greater predominance of constipation in B+D group and of diarrhea in the B group (p < 0.03). Both groups were similar in other clinical parameters, including progressive worsening of symptoms during the day, and relief by passing stool or gas. Both bloating and distension worsened when other abdominal symptoms worsened. Abdominal distension was associated with greater symptom severity and less diurnal variation in symptoms, and was less often perceived as associated with food intake. CONCLUSIONS: Bloating and visible abdominal distension may arise from two distinct but interrelated physiological processes. Although the sensation of bloating may be related to enhanced sensitivity to visceral afferent stimulation, abdominal distension in more severely affected patients may be related to triggering of a visceromotor reflex affecting the tone of abdominal wall muscles.     

Impaired viscerosomatic reflexes and abdominal-wall dystony associated with bloating

BACKGROUND & AIMS: Abdominal bloating is a frequent complaint in irritable bowel syndrome (IBS), but its underlying mechanism remains uncertain. Our aim was to determine whether the abdominal wall, specifically its adaptation to intra-abdominal volumes, plays a role. METHODS: In 12 patients complaining of abdominal bloating (8 IBS and 4 functional bloating) and in 12 healthy controls, the effect of colonic gas load (24 mL/min rectal gas infusion for 1 hour) on perception (measured by a 0-6 scale), abdominal girth, and muscular activity was tested. With the participants sitting on an ergonomic chair and the trunk erect, multichannel electromyography was measured via bipolar surface electrodes located over the upper and lower rectus abdominis, and the external and internal oblique bilaterally. RESULTS: In healthy controls, colonic gas loads produced subjective symptoms (score, 3.0 +/- 0.3), objective abdominal distention (girth increment, 6 +/- 1 mm), and increased the activity of the abdominal muscles (external oblique activity, 11% +/- 3% in; P < .05 vs basal). At the same infused gas volumes, the patients developed significantly more symptoms (score, 4.5 +/- 0.4) and abdominal distention (11 +/- 1 mm; P < .05 vs healthy for both). These abnormal responses were associated with failed tonic contraction of the abdominal wall (external oblique activity change, -1% +/- 4%; P value not significant vs basal) and paradoxic relaxation of the internal oblique (activity reduction, 26% +/- 7%; P < .01 vs basal). CONCLUSIONS: In patients with bloating, abdominal perception and distention in response to intra-abdominal volume increments are exaggerated markedly and associated with muscular dystony of the abdominal wall.     

A randomized double-blind placebo-controlled trial of rifaximin in patients with abdominal bloating and flatulence

AIMS: To study the efficacy of rifaximin, a nonabsorbable antibiotic, in relieving chronic functional symptoms of bloating and flatulence. METHODS: Randomized double-blind placebo-controlled trial consisting of three 10-day phases: baseline (phase 1), treatment with rifaximin 400 mg b.i.d. or placebo (phase 2), and post-treatment period (phase 3). Primary efficacy variable was subjective global symptom relief at the end of each phase. A symptom score was calculated from a symptom diary. Lactulose H2-breath test (LHBT) was performed at baseline and end of study. RESULTS: One hundred and twenty-four patients were enrolled (63 rifaximin and 61 placebo). Baseline characteristics were comparable and none had an abnormal baseline LHBT. Rome II criteria were met in 58.7% and 54.1%, respectively. At the end of phase 2, there was a significant difference in global symptom relief with rifaximin versus placebo (41.3% vs 22.9%, p = 0.03). This improvement was maintained at the end of phase 3 (28.6% vs 11.5%, p = 0.02). Mean cumulative and bloating-specific scores dropped significantly in the rifaximin group (p < 0.05). Among patients with IBS, a favorable response to rifaximin was noted (40.5% vs 18.2%; p = 0.04) persisting by the end of phase 3 (27% vs 9.1%; p = 0.05). H2-breath excretion dropped significantly among rifaximin responders and correlated with improvement in bloating and overall symptom scores (p = 0.01). No adverse events were reported. CONCLUSIONS: Rifaximin is a safe and effective treatment for abdominal bloating and flatulence, including in IBS patients. Symptom improvement correlates with reduction in H2-breath excretion. Future trials are needed to examine the efficacy of long-term or cyclic rifaximin in functional colonic disorders.     

Impaired transit of chyme in chronic intestinal pseudoobstruction. Correction by cisapride

Chronic intestinal pseudoobstruction is a clinical syndrome whose pathophysiology, objective diagnosis, and treatment are poorly understood. We investigated 8 patients with this syndrome in whom intestinal dysmotility was established manometrically by two or more of the following criteria: abnormal configuration or propagation of interdigestive motor complexes, sustained incoordinate pressure activity, non-propagated bursts of phasic pressure activity, and failure of a solid-liquid meal to induce a fed pattern. To establish the functional impairment and region of the gut primarily affected by the disease, we quantified radio-scintigraphically the gastrointestinal transit of the solid (131I-fiber) and liquid (99 mTc-DTPA) components of a meal. Our techniques allowed us to quantify separately gastric emptying and pylorus-to-cecum transit. Furthermore, we evaluated the effects of a new prokinetic agent, cisapride. Gastric emptying times in pseudoobstruction were not significantly delayed; however, transit times through the small bowel (t1/2) were markedly prolonged [solids, 235 +/- 43 min (mean +/- SEM) vs. 138 +/- 25 controls, p less than 0.05; liquids, 310 +/- 67 vs. 181 +/- 28 controls, p = 0.07]. Cisapride was effective in reducing the delayed intestinal transit time to within the normal range (delta solids = -115 +/- 25 min; delta liquids = -146 +/- 71 min; p less than 0.05 for both). These studies suggest that intestinal dysmotility in this group of patients with pseudoobstruction was associated with delayed small bowel transit of radiolabeled solid and liquid components of chyme. Cisapride can restore to normal the delayed transit, indicating that it may potentially correct the impaired propulsive activity in the small bowel of these patients.     

Impaired intestinal barrier in patients with obstructive sleep apnea

Background

Obstructive sleep apnea (OSA) is often associated with multisystem damage. The gut is a pivotal organ that initiates the pathophysiological processes of multisystem diseases. Intermittent hypoxia resulting from OSA may impair the intestinal barrier prior to the induction of systemic inflammation. We hypothesize that the intestinal barrier markers D-lactic acid (D-LA) and intestinal fatty acid–binding protein (I-FABP) levels would be higher in patients with OSA.

Methods

Consecutive snoring and nonsnoring adults were included in this study and were grouped based on their apnea-hypopnea index (AHI) scores: the control group (AHI < 5) and the OSA group (AHI ≥ 5). Plasma D-LA and I-FABP levels were measured using colorimetry and ELISA, respectively. Other parameters, such as fasting levels of lipids, routine blood tests, and glucose were also assessed.

Results

Of 76 participants, patients in the OSA group accounted for 73% (55/76). Plasma D-LA and I-FABP levels were significantly higher in patients with OSA [7.90 (7.42) (IQR) vs. 0.88 (2.79) (IQR) mmol/L, p < 0.001 and 1851.99 ± 754.23 (SD) vs. 1131.98 ± 383.38 pg/mL, p < 0.001, respectively]. Increased glucose, triglycerides (TGs), leukocytes, neutrophils, and monocytes but decreased high density lipoprotein (HDL) were also found in patients with OSA. It was also observed that the increase in D-LA and I-FABP exhibited the strongest positive association with AHI (r = 0.443, p < 0.001; r = 0.645, p < 0.001), followed by the lowest SaO2 (p ≤ 0.001), BMI (p ≤ 0.017), glucose (p ≤ 0.011), and TGs (p ≤ 0.025). Moreover, multivariate regression analysis showed that D-LA (B = 0.823, p < 0.001) and I-FABP (B = 0.002, p = 0.017) were independently associated with OSA.

Conclusions

The systemic expression of D-LA and I-FABP is dramatically higher in OSA patients, suggesting that hypoxia resulting from OSA might have the capacity to impair the intestinal barrier prior to the induction of multisystem dysfunction.

     

Impaired swallowing reflex in patients with obstructive sleep apnea syndrome.

BACKGROUND: The swallowing reflex is well coordinated with breathing patterns in normal humans. However, patients with obstructive sleep apnea syndrome (OSAS) may have a swallowing disorder that reflects the abnormal function of nerves and muscles in the suprapharynx. OBJECTIVE: To examine the relationship between the swallowing function and sleep-disordered breathing in patients with OSAS. PARTICIPANTS: Twenty patients with OSAS with a mean (+/-SD) age of 53.4+/-8.9 years old, and 20 age-matched control subjects with a mean age of 51.4+/-9.1 years old. METHODS: OSAS was diagnosed using the recordings of overnight polysomnography. The swallowing function in the subject was tested using a swallowing provocation test. The swallowing reflex was determined according to the following criteria: latent time (LT), the time following a bolus injection of distilled water at the suprapharynx to the onset of swallowing; inspiratory suppression time (IST), the time from the termination of swallowing to the next onset of inspiration; and threshold volume, the minimum volume of water (range, 0.4 to 2 mL) that could evoke the swallowing response. RESULTS: Whereas the LT values in patients with OSAS were larger than the LT values in the control subjects, the IST values (which may reflect the switching mechanism from deglutition apnea to breathing) were actually shorter. In addition, a greater bolus volume was necessary to elicit swallowing in patients with OSAS than was necessary in the control subjects. CONCLUSION: Patients with OSAS are likely to exhibit an impaired swallowing reflex, probably due to the perturbed neural and muscular function of the upper airways.     

Pelvic floor dysfunction predicts abdominal bloating and distension in eating disorder patients

Abstract

Objective. Little is known about the symptoms of abdominal bloating and distension in women with eating disorders (EDs). This study aimed to explore the prevalence and predictors of these symptoms in patients with EDs, by examining correlations with functional gastrointestinal disorders (FGIDs) including pelvic floor symptoms and other clinical features. Material and methods. 184 ED inpatients, 16–55 years, completed on admission to hospital the ROME II symptom questionnaire, additional questions about abdominal bloating and distension, and psychological questionnaires. Prediction of abdominal bloating and distension was modeled using logistic regression analyses with individual FGIDs, psychological variables, ED type, and clinical features as the potential predictors. Results. Bloating (78%) was more common than distension (58%) in each ED type. In the final multivariate models, after controlling for BMI, the number of Rome II symptoms of pelvic floor dyssynergia (i.e., having to strain to pass a stool, feeling unable to empty the rectum, and having difficulty relaxing to evacuate the stool) was a significant predictor of both abdominal distension (p < 0.001) and bloating (p < 0.005). The presence of irritable bowel syndrome (IBS, 46%) was a significant predictor of bloating (p < 0.001) but not distension. Conclusions. Symptoms of pelvic floor dysfunction, but not IBS, appear to be especially important in the genesis of abdominal distension in patients with ED.     

Influence of body posture on intestinal transit of gas

BACKGROUND: Patients describe that body posture may affect their abdominal bloating, distension, and flatulence, but whether changes in position have objectively demonstrable effects, either beneficial or deleterious, has not been investigated. Aim: To determine the effect of body posture, upright versus supine, on intestinal transit of gas loads. SUBJECTS: Eight healthy subjects without gastrointestinal symptoms. METHODS: In each subject a gas mixture was continuously infused into the jejunum (12 ml/min) for three hours, and gas evacuation, clearance of a non- absorbable gaseous marker, perception, and abdominal girth were measured. Paired studies were randomly performed in each subject on separate days in the upright and supine positions. RESULTS: In the upright position, intestinal gas retention was much smaller than when supine (13 (52) ml v 146 (75) ml retention at 60 minutes, respectively; p<0.05), and clearance of the gas marker was expedited (72 (10)% clearance v 49 (16)% at 60 minutes, respectively; p<0.05). The gas challenge test was well tolerated both in the upright and supine positions without abdominal distension. CONCLUSION: Body posture has a significant influence on intestinal gas propulsion: transit is faster in the upright position than when supine.